Two-dimensional real-time quality assurance dosimetry system using μ-Al2O3:C,Mg radioluminescence films

Abstract

Background and purpose: There is a continual need for more accurate and effective dosimetric systems for quality assurance (QA) as radiotherapy evolves in complexity. The purpose of this project was to introduce a new system that minimally perturbs the main beam, while assessing its real time 2D dose-rate and field shapes. The system combined reusability, linear dose-rate response, and high spatial and time resolution in a single radiation detection technology that can be applied to surface dose estimation and QA. Materials and methods: We developed a 2D prototype system consisting of a camera, focusing lenses and short pass filter, placed on the head of a linear accelerator, facing an Al 2 O 3 :C,Mg radioluminescent film. To check the appropriateness of multi-leaf collimator, stability/reproducibility QA tests were prepared using the treatment planning system: including the routinely used alternating leaves, chair and pyramid checks. Results: The Al 2 O 3 :C,Mg film did not perturb the dose vs. depth dose curves determined with a point detector (-0.5% difference). Our results showed a dose-rate linear film response (R 2 = 0.999), from 5 to 600 MU/min. Measured output factors agreed with reference data within ~1%, indicating a potential for small field dosimetry. Both chair and pyramid measured profiles were comparable with those obtained with the treatment planning system within 1%. The alternating leaves test showed an average discrepancy in the valleys of 14%. Conclusions: The prototype demonstrated promising results. It obviated the need for corrections regarding the relative position of the camera, confirming accurate dose-rate delivery and detection of radiation fields.

Ultra‐high dose rate dosimetry: Challenges and opportunities for FLASH radiation therapy

“…OSLDs are traditionally passive and readout post‐irradiation, which is quite suitable for dosimetry applications. More recently, active readout methods have emerged, which may find use in both dosimetry and beam monitoring applications 117–121 . While the dose rate response of OSLDs relevant to FLASH RT is yet to be fully tested, 114,122 fast readout and reliable dose measurement after repeat bleaching could alleviate dose rate effects 123 …”

“…More recently, active readout methods have emerged, which may find use in both dosimetry and beam monitoring applications. [117][118][119][120][121] While the dose rate response of OSLDs relevant to FLASH RT is yet to be fully tested, 114,122 fast readout and reliable dose measurement after repeat bleaching could alleviate dose rate effects. 123 The lower sensitivity of OSLDs to radiation was considered a disadvantage, however this may be useful in FLASH radiation environments.…”

Radioluminescence imaging feasibility for robotic radiosurgery field size quality assurance

“…The use of radioluminescent phosphor‐based radiation visualization technique has made it possible to provide a practical, reliable, and useful tool for radiation beam monitoring and quality control. 18 , 19 , 20 , 21 This method is known as radioluminescence imaging (RLI) or scintillation imaging and is based on a radioluminescence screen imaged with commercial complementary metal oxide semiconductor (CMOS) or charge coupled device (CCD) camera. The screen is used for the detection and conversion of X‐rays to photons within the visible range.…”

Spectral fiber dosimetry with beryllium oxide for quality assurance in hadron radiation therapy

“…A solution could be the use of radioluminescent materials and their sensitivity to ionizing radiation. Radioluminescent probes, where a small luminophore is placed on the tip of a long and flexible light guide, can yield accurate dose readings with a very robust signal transmission [5][6][7][8]. The signal output allows for very small sensitive volumes (< 1 mm 3 ) and therefore good spatial 2022 JINST 17 P02009 resolution.…”